diff --git a/lib/rb/thrift.gemspec b/lib/rb/thrift.gemspec
index 3ee7e7c..c6f32cb 100644
--- a/lib/rb/thrift.gemspec
+++ b/lib/rb/thrift.gemspec
@@ -31,7 +31,7 @@
   s.add_development_dependency 'pry',                '~> 0.11.3'
   s.add_development_dependency 'pry-byebug',         '~> 3.6'
   s.add_development_dependency 'pry-stack_explorer', '~> 0.4.9.2'
-  s.add_development_dependency 'rack',               '~> 2.0'
+  s.add_development_dependency 'rack',               '=  2.0.8'
   s.add_development_dependency 'rack-test',          '~> 0.8.3'
   s.add_development_dependency 'rake',               '~> 12.3'
   s.add_development_dependency 'rspec',              '~> 3.7'